Expression of insulin/insulin-like signalling and TOR pathway genes in honey bee caste determination.

The development of queen and worker castes in honey bees is induced by differential nutrition, with future queens and workers receiving diets that are qualitatively and quantitatively different. We monitored the gene expression of 14 genes for components of the insulin/insulin-like signalling and TOR pathways in honey bee larvae from 40-88 h after hatching. We compared normally fed queen and normally fed worker larvae and found that three genes showed expression differences in 40-h-old larvae. Genes that show such early differences in expression may be part of the mechanism that transduces nutrition level into a hormone signal. We then compared changes in expression after shifts in diet with those in normally developing queens and workers. Following a shift to the worker diet, the expression of 9/14 genes was upregulated in comparison with queens. Following a shift to the queen diet, expression of only one gene changed. The honey bee responses may function together as a homeostatic mechanism buffering larvae from caste-disrupting variation in nutrition. The different responses would be part of the canalization of both the queen and worker developmental pathways, and as such, a signature of advanced sociality.

Collapsing glomerulopathy in a patient with mixed connective tissue disease.

Collapsing glomerulopathy (CG) is a distinct clinicopathological entity characterized by glomerular capillary collapse, podocyte proliferation, diffuse mesangial sclerosis, and podocyte maturation arrest. Initially noted primarily in HIV infected patients, a number of other diseases have now been associated with CG. Mixed connective tissue disease (MCTD) is a disease with overlapping features of systemic lupus erythematosus, progressive systemic sclerosis, and polymyositis. It was originally thought that renal involvement was a rare complication of MCTD. However, over the years, it has become clearer that renal involvement, although not always clinically apparent, is frequent. In this report we present a patient with MCTD who developed CG.

Soldier determination in ants: new role for juvenile hormone.

Topical application of juvenile hormone analog induces soldier development in the ant Pheidole bicarinata. Soldier induction takes place if the juvenile hormone analog is present during a period of sensitivity that occurs during the last larval instar. Control of worker dimorphism seems to be accomplished through control of timing of metamorphosis. The smallest size at which metamorphosis can be initiated is shifted upwardfrom 1.2 to 1.7 millimeters by exposure to the juvenile hormone analog during the sensitive period.

Internal reproductive system in adult males of the genus Camponotus (Hymenoptera: Formicidae: Formicinae).

Descriptions are provided of the histology and ultrastructure of the male internal reproductive tracts from three species of Camponotus, representing three subgenera. This study is the first to provide ultrastructural information on the testes (including spermatogenesis and spermiogenesis), seminal vesicles, and accessory glands in ants. Testes contain about ten follicles each, and each follicle is capable of producing hundreds of cysts in which spermatozoa develop. Structural evidence of meiosis in late pupal testes includes cytoplasmic bridges between spermatocytes, centriole elimination, and fusion of mitochondria. Developing spermatids are in close contact with cyst cells in the region of the acrosome. Mature spermatozoa are similar in ultrastructure to those described previously for two other subfamilies of ants (Myrmicinae and Dolichoderinae). The ultrastructure of the seminal vesicle suggests that it is not merely a passive organ for sperm storage. Large numbers of both mitochondria and membranous whorls suggest a pH-regulating and/or hormonal function. The accessory gland is made up of secretory cells that contain a diversity of secretory granules. SDS-PAGE reveals several proteins found in the accessory glands but absent in the adjacent genitalia. Preliminary analyses indicate that carbohydrate is an important component of accessory gland secretions.

Comparative ultrastructure of ant spermatozoa (Formicidae: Hymenoptera).

Mature spermatozoa from spermathecae of founding queens were obtained from 5 species of ants, representing the major subfamilies Myrmicinae (Acromyrmex versicolor, Crematogaster sp.) and Dolichoderinae (Tapinoma sessile, Conomyrma insana, Conomyrma wheeleri). The ultrastructure of ant spermatozoa has many features in common with that of higher insects and is similar to that of other Hymenoptera. Structural similarities to spermatozoa of other Hymenoptera include an acrosome containing an internal rod that extends into the nucleus, two elongate mitochondrial derivatives, a centriolar adjunct, and an axonemal arrangement of 9 + 9 + 2 that includes well-developed coarse, or accessory, tubules. Spermatozoa obtained from A. versicolor, a species that is known to store and utilize viable sperm from this supply for over 10 years, show greater development of the mitochondrial derivatives than do the other species. The most distinctive feature of ant spermatozoa in comparison to other Hymenoptera is the large size of the centriolar adjunct relative to the other organelles. The centriolar adjunct is located posterior to the nucleus, anterior to the mitochondrial derivatives, and opposite the axoneme.

Storage proteins in ants (Hymenoptera:Formicidae).

Storage proteins are a major feature of holometabolous development in insects, accumulating during the larval period and disappearing during metamorphosis. In ants (Hymenoptera:Formicidae), storage proteins also play important roles in adult females. Three types of storage proteins have been characterized from ants: hexamerins, proteins high in glutamine/glutamic acid, and very high density lipoproteins (VHDLs). The hexamerins have moderately high levels of aromatic amino acids and belong to the arthropod hemocyanin family of proteins. The proteins high in glutamine/glutamic acid can form hexamers under some conditions, but the subunit size is larger than that of typical hexamerins. The VHDLs are dimeric and share features with storage chromoproteins described from Lepidoptera. In Camponotus festinatus (Formicinae), storage proteins are found in adult ants in two situations. First, lack of brood stimulates workers to accumulate the same two storage hexamers found in larvae. Second, young virgin queens store large reserves of these proteins before mating. Protein storage by queens has been confirmed in two other subfamilies of ants, indicating it is widespread. The capacity to store proteins as adults enables queens to rear brood without leaving the nest and workers to store rich reserves and regulate larval diet seasonally.

Expression of insulin pathway genes during the period of caste determination in the honey bee, Apis mellifera.

Female honeybees have two castes, queens and workers. Developmental fate is determined by larval diet. Coding sequences made available through the Honey Bee Genome Sequencing Consortium allow for a pathway-based approach to understanding caste determination. We examined the expression of several genes of the insulin signalling pathway, which is central to regulation of growth based on nutrition. We found one insulin-like peptide expressed at very high levels in queen but not worker larvae. Also, the gene for an insulin receptor was expressed at higher levels in queen larvae during the 2nd larval instar. These results demonstrate that the insulin pathway is a compelling candidate for pursing the relationship between diet and downstream signals involved in caste determination and differentiation.

Gene expression and the evolution of insect polyphenisms.

Polyphenic differences between individuals arise not through differences at the genome level but as a result of specific cues received during development. Polyphenisms often involve entire suites of characters, as shown dramatically by the polyphenic castes found in many social insect colonies. An understanding of the genetic architecture behind polyphenisms provides a novel means of studying the interplay between genomes, gene expression and phenotypes. Here we discuss polyphenisms and molecular genetic tools now available to unravel their developmental bases in insects. We focus on several recent studies that have tracked gene-expression patterns during social insect caste determination. BioEssays 23:62-68, 2001. Published 2001 John Wiley & Sons, Inc.

Expression profiles during honeybee caste determination.

BACKGROUND: Depending on their larval environment, female honeybees develop into either queens or workers. As in other polyphenisms, this developmental switch depends not on genomic differences between queens and workers but on the differential expression of entire suites of genes involved with larval fate. As such, this and other polyphenic systems can provide a novel tool for understanding how genomes and environmental conditions interact to produce different developmental trajectories. Here we use gene-expression profiles during honeybee caste determination to present the first genomic view of polyphenic development. RESULTS: Larvae raised as queens or workers differed greatly in their gene-expression patterns. Workers remained more faithful than queens to the expression profiles of younger, bipotential, larvae. Queens appeared to both downregulate many of the genes expressed by bipotential larvae and turn on a distinct set of caste-related genes. Queens overexpressed several metabolic enzymes, workers showed increased expression of a member of the cytochrome P450 family, hexameric storage proteins and dihydrodiol dehydrogenase, and young larvae overexpressed two putative heat-shock proteins (70 and 90 kDa), and several proteins related to RNA processing and translation. CONCLUSIONS: Large differences in gene expression between queens and workers indicate that social insect castes have faced strong directional selection pressures. Overexpression of metabolic enzymes by queen-destined larvae appears to reflect the enhanced growth rate of queens during late larval development. Many of the differently expressed genes we identified have been tied to metabolic rates and cellular responses to hormones, a result consistent with known physiological differences between queen and worker larvae.

Morphological commitment in Candida albicans.

Stationary phase yeast cells of the dimorphic fungus albicans can reinitiate growth under appropriate conditions either as yeasts through bud formation or as hyphae through germ tube formation and elongation. Stationary phase yeast cells resuspended in fresh medium at 37 degrees C form germ tubes and those resuspended at 25 degrees C form buds. Temperature shift experiments have been used to observe when cells become committed to germ tube formation and yeast budding growth under conditions favorable to each form. The two commitment processes appear to be independent and, once initiated, occur at characteristic rates with commitment to germ tube formation preceding commitment to yeast bud formation. The rate of commitment to germ tube formation was consistent with a random process or first-order kinetics. A relationship between cell volume and commitment to yeast growth and bud emergence was consistent with observations of cell volume distribution both in stationary phase cultures and between budded and unbudded cells during resumption of growth at 25 degrees C.

Differential gene expression between developing queens and workers in the honey bee, Apis mellifera.

Many insects show polyphenisms, or alternative morphologies, which are based on differential gene expression rather than genetic polymorphism. Queens and workers are alternative forms of the adult female honey bee and represent one of the best known examples of insect polyphenism. Hormonal regulation of caste determination in honey bees has been studied in detail, but little is known about the proximate molecular mechanisms underlying this process, or any other such polyphenism. We report the success of a molecular-genetic approach for studying queen- and worker-specific gene expression in the development of the honey bee (Apis mellifera). Numerous genes appear to be differentially expressed between the two castes. Seven differentially expressed loci described here belong to at least five distinctly different evolutionary and functional groups. Two are particularly promising as potential regulators of caste differentiation. One is homologous to a widespread class of proteins that bind lipids and other hydrophobic ligands, including retinoic acid. The second locus shows sequence similarity to a DNA-binding domain in the Ets family of transcription factors. The remaining loci appear to be involved with downstream changes inherent to queen- or worker-specific developmental pathways. Caste determination in honey bees is typically thought of as primarily queen determination; our results make it clear that the process involves specific activation of genes in workers as well as in queens.

Purification and characterization of honey bee vitellogenin.

A protocol has been developed for the purification of vitellogenin from the honey bee, Apis mellifera. Purification allows for the first characterization of a vitellogenin from the large order Hymenoptera. Hymenopteran vitellogenins are unusual among insect vitellogenins in that they contain only one type of apoprotein. The honey bee vitellogenin was isolated from hemolymph of honey bee queens by a combination of density gradient ultracentrifugation, ion-exchange chromatography, and affinity chromatography. The native vitellogenin particle is a very high density glycolipoprotein containing approximately 91% protein, 7% lipid, and 2% carbohydrate. Phospholipid and diacylglycerol are the major lipid components. The equilibrium density (1.28 g/ml) is the same as that for Manduca sexta vitellogenin, which contains a much higher proportion of lipid. The covalently bound carbohydrate moiety of the particle is high in mannose. The amino acid composition of vitellogenin is similar to those of vitellogenins from other insect species. The N-terminal amino acid sequence of the apoprotein was determined, the first such sequence for any insect vitellogenin. When analyzed by sodium dodecyl sulfate (SDS)-gel electrophoresis, A. mellifera vitellogenin resolved into a single band with an apparent Mr of 180,000. Gel filtration under reducing and native conditions yielded estimated Mr values of about 300,000.

Leprosy-associated renal disease: case report and review of the literature.

Leprosy is an infectious disease the principal clinical manifestations of which are anesthetic skin lesions and the development of peripheral neuropathy. The most common renal manifestation in leprosy patients is glomerulonephritis. Both immunofluorescent and electron microscopic studies suggest that the varied glomerular lesions found in these patients are immune complex mediated. Other renal lesions that have been described include amyloidosis, tubulointerstitial disease, acute renal failure, and functional defects in the absence of identifiable histologic abnormalities. In this report, a patient is described who developed the clinical syndrome of rapidly progressive glomerulonephritis. The renal biopsy showed a diffuse endocapillary proliferative process with electron-dense deposits in the glomerular subendothelial and subepithelial spaces. Organisms consistent with Mycobacterium leprae were identified within several of the glomeruli.

Response of storage protein levels to variation in dietary protein levels.

Storage proteins have been found to play a major role in insect metamorphosis and egg production and are accumulated during the actively feeding larval stage. Yet few studies have focused on how nutrition affects storage protein levels. Three storage proteins were identified in male and female Heliothis virescens pupae, one arylphorin and two putative high-methionine hexamers. Storage proteins were quantified in early pupae and in pharate adults. Storage protein levels peaked in 48-h pupae and were more abundant in females across all stages. Both male and female pharate adults retained a portion of total storage protein levels and females retained greater levels overall. In females, post-eclosion protein reserves will likely be used toward egg manufacturing, while the role of protein reserves in males remains speculative. In our previous study of H. virescens larvae, we found that protein-derived growth in females progressively increased as dietary protein levels increased. Our present data show that levels of storage protein also increased progressively along with dietary protein levels. This suggests that females allocated protein, in excess of adult tissue formation needs, toward storage protein. Our study is the first to demonstrate how responsive storage protein levels can be in face of varying levels of dietary protein.

Ameloblastoma associated with basal cell nevus (Gorlin) syndrome: CT findings.

Multiple jaw cysts are a characteristic manifestation of basal cell nevus (Gorlin) syndrome. In contrast to the frequent odontogenic keratocysts, ameloblastoma only rarely occurs in the jaw. Computed tomography is essential to delineate the extent of these radioresistant lesions, which must undergo marginal resection. We present such a case, not only to stress the importance of CT evaluation but also to briefly review the unusual association of ameloblastoma with Gorlin syndrome.

Expression of cytosolic beta-glucosidase in guinea pig liver cells.

The cytosolic beta-glucosidase of mammalian liver has been implicated in the metabolic transformation of plant glycosides, such as vicine and amygdalin, which are associated with the development of toxic syndromes. We investigated which cell types express cytosolic beta-glucosidase in guinea pig liver, and characterized the contribution of this enzyme to the hydrolysis of aromatic glucosides in cultured cells and in tissue slices. Cytosolic beta-glucosidase was expressed in hepatocytes and not in Kupffer or endothelial cells as determined by enzyme-specific activity and Western blots of liver cell extracts. Intracellular beta-glucosidase activity was visualized using the fluorescent beta-glucosidase substrate, resorufin beta-D-glucoside, and shown to be caused by the cytosolic beta-glucosidase using the inhibitors, conduritol beta-epoxide and dinitrophenol-2-deoxy-2-fluoro-beta-D-glucopyranoside (DNP2FGlc). Staining of fresh liver slices with resorufin beta-glucoside revealed that cytosolic beta-glucosidase is expressed in all hepatocytes, with no significant portal-central gradient. These data indicate that cytosolic beta-glucosidase is a hepatocyte-specific enzyme, and support the hypothesis that cytosolic beta-glucosidase in the liver functions to hydrolyze small glucosides absorbed by the intestine. Furthermore, toxic injury to cultured hepatocytes by CCl4 resulted in release of cytosolic beta-glucosidase in parallel with the hepatocyte marker enzymes alanine transaminase and lactate dehydrogenase. This suggests that acute increases in serum levels of cytosolic beta-glucosidase in animal models of liver injury may reflect direct injury of hepatocytes.

Bimolecular electron and energy transfer reactivity of exchange-coupled dinuclear iron(III) complexes.

Bimolecular quenching between photosensitizers and exchange-coupled transition metal complexes has been studied in an effort to experimentally establish a link between Heisenberg spin exchange and chemical reactivity. The acceptors are members of the oxo/hydroxo-biscarboxylato class of dinuclear Fe(III) compounds, where protonation of the oxo bridge provides a means for modulating the magnitude of spin exchange within the cluster. Photoexcitation of solutions containing Ru(II) polypyridyl sensitizers and the Fe(III) complexes results in quenching of emission from the (3)MLCT excited state of the Ru(II) chromophores; nanosecond time-resolved absorption measurements demonstrate that quenching occurs, in part, by electron transfer. Decoupling electron transfer driving force (DeltaG(0)(ET)) from changes in the magnitude of spin exchange was achieved by varying the bridging carboxylate to afford a series of complexes of the form [Fe(2)O(H)(O(2)CR)(2)(Tp)(2)](n)(+) (n = 0, 1, 2). Electrochemical measurements reveal a greater than 500 mV shift in cluster reduction potential across the series (i.e., R = CH(3) to CF(3)), whereas variable-temperature magnetic susceptibility measurements demonstrate a corresponding invariance in spin exchange between the metal centers (J(oxo) = -119 +/- 4 cm(-1) and J(hydroxo) = -18 +/- 2 cm(-1) for H = -2JS(1).S(2)). Structural analyses suggest that reorganization energies (lambda) associated with electron transfer should be identical for all molecules within a given series (i.e., oxo or hydroxo bridged); likewise Deltalambda between the series is expected to be small. A comparison of quenching rates for the two extended series firmly establishes that neither reorganization energy nor electron transfer driving force considerations can account for differences in reactivity between oxo-bridged (large spin exchange) and hydroxo-bridged (small spin exchange) quenchers. Upon consideration of energy transfer contributions, it is determined that reactivity differences between the oxo- and hydroxo-bridged quenchers must lie in the relative rates of Dexter energy transfer and/or electron transfer, with the origin of the latter linked to something other than DeltaG(0)(ET) or lambda. Finally, the extent to which spin exchange within the dinuclear Fe(III) quenchers can be identified as the key variable influencing these reactivity patterns is discussed.

How female caterpillars accumulate their nutrient reserves.

Female Lepidoptera are often heavier than males. We examined the importance of consumption and post-ingestive processing as mechanisms for female Heliothis virescens larvae to meet the protein and carbohydrate requirements. In experiments in which caterpillars had a choice of diets, enabling them to select an appropriate protein and carbohydrate intake, females caterpillars ate more carbohydrate than males, but only on the heavily carbohydrate biased treatment. Overall, the sexes were not distinguished according to the selective feeding behavior, but females accumulated more protein and carbohydrate over the whole instar than the males did. Additionally, when given no choice, females ate more than males and accumulated more protein provided the diet contained a high proportion of protein. If they were reared on a high carbohydrate diet, there were no differences between the sexes. Our results indicate that female H. virescens larvae accumulate protein by regulating both intake and post-ingestive processing on high protein foods. In the field, late instar H. virescens feed on anthers, which are protein-rich and have the highest amino acid content relative to other cotton floral tissues.

Proliferative activity of cyst epithelium in human renal cystic diseases.

Increased proliferative activity of the renal tubular epithelium is thought to be a prerequisite for renal cyst formation by many investigators. However, in humans, the exact in vivo proliferation rate of epithelial cells lining these cysts is not known. In this study, which used immunohistochemical methods with an antibody to proliferating cell nuclear antigen (PCNA), the proliferation index (PI) (percentage of PCNA positive cell nuclei among epithelial cells lining the renal cysts) was determined in 10 cases of autosomal dominant polycystic kidney disease (ADPKD), 8 cases of autosomal recessive polycystic kidney disease (ARPKD), and 8 cases of acquired cystic kidney disease (ACKD). Cysts with proximal and distal nephron phenotype and cysts with markedly thickened basement membranes, as well as cysts lined by atrophic (flattened), "regular" (cuboidal or cylindrical), and hyperplastic epithelium, were evaluated separately. The overall PI of cyst epithelium (excluding hyperplastic cysts) was 2.58 in ADPKD, was 10.5 in ARPKD, and was 3.61 in ACKD. Overall, there were only minor differences in the PI between the various types of cysts. Cysts with hyperplastic epithelium in ACKD (unlike in ADPKD) showed a high PI (9.1). For comparison, the PI of two renal cell carcinomas occurring in two ACKD cases was also determined (13.70 and 8.67%). The PI of tubular epithelium in normal kidneys was only 0.22 to 0.33%, depending on the tubule segment. In contrast, in polycystic kidneys, those noncystic segments of the nephron from which the cysts are thought to originate (distal nephron (specifically collecting duct)) in ARPKD, primarily distal in ADPKD, proximal and distal in ACKD, had PI values similar to those of the cyst epithelium.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical features of hepatitis C-infected patients with persistently normal alanine transaminase levels in the Southwestern United States.

Approximately one third of patients with chronic hepatitis C virus (HCV) infection have normal alanine transaminase (ALT) levels. We studied the clinical, biochemical, virological, and histological features in patients with persistently normal ALT. A case-control study was conducted on 275 patients with chronic HCV infection, including 75 patients with persistently normal ALT and 200 patients with abnormal ALT. Persistently normal ALT was defined as 4 consecutive ALT values in each patient within a period of 12 months. The average age of the patients was 44 years (range 18 to 69 years). More non-Hispanic whites had persistently normal ALT. The mean serum ferritin level was significantly lower in patients with persistently normal ALT as compared with abnormal ALT (128 +/- 92 ng/mL and 224 +/- 128 ng/mL), respectively (P =.017). The mean HCV-RNA level was significantly lower in patients with persistently normal ALT as compared with abnormal ALT (12 x 10(5) +/- 2.8 x 10(6) copies/mL and 33 x 10(5) +/- 8.0 x 10(6)), respectively (P =.02). Histologically, patients with persistently normal ALT had less severe portal inflammation (P <.05), lobular inflammation (P =.003), piecemeal necrosis (P =.002), fibrosis (P <.05), lower prevalence of cirrhosis (P =.007), as well as a slower fibrosis progression rate (P <.001). Chronic hepatitis C patients with persistently normal ALT have low-activity grade and stage on liver biopsy. In these patients the hepatitis C RNA level was lower compared with abnormal ALT patients, which may explain the slower fibrosis progression rate.